Mechanical Dyssynchrony for Prediction of the Cardiac Resynchronization Therapy Response in Patients with Dilated Cardiomyopathy.

Aim      To evaluate the predictive value of indexes of left ventricular mechanical dyssynchrony (MD) as determined by data of electrocardiogram (ECG)-gated myocardial perfusion scintigraphy (ECG-MPS) for prediction of the efficacy of resynchronization therapy (RT) in patients with chronic heart failure (CHF).Material and methods  This prospective study included 32 patients with nonischemic CHF and standard indications for RT. All patients underwent complete clinical an instrumental examination, including 24-h ECG monitoring and echocardiography (EchoCG). In order to evaluate the left ventricular (LV) myocardial perfusion, contractile function, and MD, myocardial perfusion scintigraphy was performed for all patients at rest prior to RT. In addition to the perfusion defect size at rest and hemodynamic parameters, LV MD was determined. The following indexes were used for analysis of dyssynchronization: phase standard deviation (PSD), phase histogram bandwidth (HBW), and phase histogram asymmetry and steepness. The treatment efficacy was evaluated by the clinical status of patients (clinical condition evaluation scale for CHF patient) and EchoCG at 6 months following RT. The criteria for a positive response to RT were an increase in LV ejection fraction (EF) by 5% and/or a decrease in the LV end-diastolic volume by 15% compared to preoperative values.Results According to ECG-MPS findings, all patients had scintigraphic signs of severe CHF with dilated LV cavity (end-diastolic volume, EDV 246 [217; 269] ml) and also of pronounced mechanical and electrical dyssynchrony. The values of mechanical dyssynchrony were PSD 53 [41; 61], HBW 176 [136; 202], asymmetry 1.62 [1.21; 1.89], and steepness 2.81 [1.21; 3.49]. The QRS duration was 165 [155; 175] msec. Furthermore, the LV perfusion was moderately impaired (perfusion defect size 4 [3; 10] %). Mean follow-up duration after implantation of the resynchronizing device was 6±1.7 mos. According to the selected criteria, 20 (63 %) patients were considered as responders and 12 (37 %) patients as non-responders. Before implantation of the cardiac synchronizing device, responders and non-responders differed only in LV MD (PSD 44 [35; 54] vs. 63 [58; 72]; p=0.0001); HBW 158 [118; 179] vs. 205 [199; 249]; p=0.0001; asymmetry 1.77 [1.62; 2.02] vs. 1.21 [0.93; 1.31]; p=0.0001; steepness 3.03 [2.60; 3.58] vs. 1.21 [0.19; 1.46]; p=0.0001), respectively. A one-factor logistic regression analysis showed that MD values were statistically significant predictors of a positive response to RT. A multi-factor logistic analysis of phase histogram steepness (odds ratio, OR 1.196; 95 % confidence interval, CI 1.04-1.37) and PSD (OR 0.67; 95 % CI 0.47-0.97) were identified as independent predictors for the response to RT. According to results of the ROC analysis, a PSD <55 and a phase histogram steepness >1.54 may predict the effectiveness of RT (AUC= 0.92; р=0.0001).Conclusion      LV MD parameters determined with ECG-MPS allow predicting the effectiveness of RT in patients with nonischemic CHF. In this patient group, high values of standard deviation and low values of phase histogram steepness were independent predictors for the absence of response to RT after 6 mos. of follow-up.

[123 I-MIBG scintigraphy in the assessment of heart failure prognosis and effectiveness of cardiac resynchronization therapy].

Cardiac resynchronization therapy (CRT) is one of the methods of treating patients with chronic heart failure, which can reduce the mortality rate of this group. Scintigraphic assessment of sympathetic myocardial innervation allows us to evaluate the heart failure prognosis and the effectiveness of interventional treatment. The method is based on use of the radiopharmaceutical 123 I-methiodiobenzylguanidine (123 I-MIBG), which is a structural analogue of norepinephrine and is able to selectively accumulate in the sympathetic nerve endings. This review includes a brief description of norepinephrine metabolism and pharmacokinetics of 123 I-MIBG in the sympathetic nerve ending, a brief description of the study methodology and the clinical significance of this method in patients with heart failure. Particular attention is paid to the possibilities of using this method in patients with severe chronic heart failure before and after CRT.

[Effect of right ventricular myocardial contractility on the response to cardiac resynchronization therapy].

AIM: To determine the effect of right ventricular myocardial contractility on the response to cardiac resynchronization therapy (CRT). MATERIALS AND METHODS: The study included 80 patients (49 men, mean age 54±10.5) diagnosed with dilated cardiomyopathy, complete left bundle branch block, and the QRS complex width 146 to 240 ms (183±32 ms). Heart failure was NYHA FC III, ejection fraction (EF) - 30.1±3.8 %, 6­min walk test - 290.5±64.3 m, and end-diastolic volume (EDV) - 220.7±50.9 ml. 35 patients had permanent atrial fibrillation. All patients received implantable devices for CRT; complete artificial atrioventricular block was formed in patients with atrial fibrillation. LV and right ventricular (RV) contractile function was studied in all patients before and at 12 months of the implantation using equilibrium radionuclide tomoventriculography. RESULTS: At 12 months, 69 (86.25 %) patients were clinical responders to CRT and 11 (13.75 %) patients did not respond to the treatment. The responders showed positive clinical dynamics; LV EF increased from 30.1±3.8 to 42.8±4.8 % (p≤0.001), LV EDV decreased from 220.7±50.9 to 197.9±47.8 ml (p≤0.005). In non-responders, LV EF increased from 30.1±3.8 to 33.8±3.8 % (p≤0.001) and LV EDV increased from 220.7±50.9 to 227.8±27.8 ml (p≤0.001). All patients were retrospectively divided into two groups: Group 1, CRT responders and Group 2, non-responders. A study using radionuclide methods showed that in Group 1 patients, maximum RV filling velocity increased from 1.8±0.36 to 2.17±0.67 (p≤0.001) and the mean velocity of RV filling for one third of diastole increased from 1±0.28 to 1.32±0.45 (p≤0.001). In Group 2, these parameters were significantly worse by 30 and 60 %, respectively. CONCLUSIONS: Cardiac resynchronization therapy is more effective in preserved contractility of the right heart, and higher values of maximum RV filling velocity for one third of diastole may serve a prognostic criterium for a beneficial response to CRT.